1. Field of the Invention.
The present invention is directed to a two cycle stratified charge gasoline engine, and more particularly, to fuel injection structure and cylinder construction which provides far lower gasoline consumption at zero to one half full load on the engine. This fuel economy is achieved by directing a gas-air mixture into the cylinder in a predetermined path, namely, by directing the gas-air mixture along the top of a piston and then upwardly along one side of the cylinder in a generally L-shaped path. The engine of the present invention and the method of operating same provide a large improvement in part throttle fuel economy which is considered to be the prime virtue of the engine.
It also has several other advantages over contemporary designs, namely:
(1) compact size, with especially short overall length which makes it well suited to transverse engine installation;
(2) very high power output for an engine of its size and weight;
(3) fewer parts which should result in lower manufacturing costs;
(4) low combustion and exhaust temperatures in the normal driving range greatly reducing NOX emissions;
(5) a low pressure fuel injection system using standard, low cost fuel pump and injectors; and,
(6) a lubrication system which is standard automotive practice, with optional wet or dry sump.
2. Description of the Related Art.
Heretofore a number of two cycle stratified charge gasoline engines have been proposed and examples of analogous and non-analogous engines are disclosed in the following analogous and non-analogous U.S. patents:
THE HIGH SPEED INTERNAL COMBUSTION ENGINE, by Harry R. Ricardo, fourth edition, 1952, reprinted 1962, by Blackie and Son Limited, Glasgow, Scotland:
pages 194-199, describing reflected waves of exhaust gases;
page 357-359, describing the need for stratification and fuel injection to obtain good fuel economy at reduced loads; and,
pages 360-369, describing the developement of an open ended sleeve.
Article entitled xe2x80x9cIS THERE A STROKER IN YOUR FUTURE?xe2x80x9d, page 25, July 1996, xe2x80x9cCYCLE WORLDxe2x80x9d.
According to the present invention, there is provided a stratified charge two cycle engine comprising:
a cylinder having an upper and a lower end with a head at the upper end and fuel and air intake ports at the lower end;
at least one spark plug mounted in the head;
a sleeve in the cylinder having an upper end and a lower end;
the cylinder having exhaust ports at the upper end which are covered and uncovered by the upper end of the sleeve;
a piston in the sleeve and connected to a crank shaft;
a first exhaust manifold at one side of the cylinder at the upper end thereof adjacent one exhaust port in the cylinder and having first exhaust gas throttle valve means associated therewith;
at least a first and a second fuel and air intake manifolds at one side of the cylinder and at the other side of the cylinder in communication with first and second fuel and air intake ports in the cylinder;
throttle valve means in each intake manifold;
a reed cage assembly in each intake manifold adjacent the associated intake port for injecting a fuel and air mixture into the cylinder;
control means for controlling the injection of fuel and air mixture into the cylinder so that fuel and air mixture is injected into the cylinder through only one intake port when the engine is operating from zero to one half full load; and
an operating connection between the crank shaft and the sleeve for causing reciprocation of the sleeve relative to movement of the piston to open and close the exhaust ports and the air and fuel intake ports in the cylinder.
Also there is provided a method for operating the engine described above comprising the steps of:
first supplying, when the engine is operating at partial load, air to the cylinder after combustion in a cycle of the piston as the piston approaches bottom dead center;
then supplying, when the engine is operating at partial load, fuel under pressure to the reed cage;
supplying throttled air under pressure to the reed cage to cause a reed in the cage to move slightly to aspirate fuel into the flowing air to create a mist-like mixture of fuel and air which is expressed into the cylinder on one side only while pressurized air is entering the cylinder through other air intake ports in the cylinder;
while exhaust gases are exiting the cylinder at the top of the cylinder such that the fuel and air mixture enters the cylinder above the piston travels radially inwardly and then upwardly in a generally L-shaped path toward the cylinder head and along the other side of the cylinder;
closing the exhaust ports with the sleeve with the air and fuel mixture being compressed in the cylinder by the upward movement of the piston; and,
causing combustion of the fuel and air mixture in the cylinder.